Enantiomers of A2-73, analogues, and sigma agonist activity

ABSTRACT

A pharmaceutical preparation comprising {circle around (−)} A2-73 substantially free of ⊕ A2-73. This invention further includes a method treating Alzheimer&#39;s disease in a subject in need of such treatment by the method of administering a therapeutically effective amount of {circle around (−)} A2-73 substantially free of ⊕ A2-73.This invention yet further includes a method of classifying cells as to sigma receptor type by the method of exposing said cells to a detectable amount of {circle around (−)} A2-73 substantially free of ⊕ A2-73 and determining the level of sigma receptor binding.

FIELD OF THE INVENTION

A pharmaceutical preparation comprising {circle around (−)} A2-73 substantially free of ⊕ A2-73. This invention further includes a method treating Alzheimer's disease in a subject in need of such treatment by the method of administering a therapeutically effective amount of {circle around (−)} A2-73 substantially free of ⊕ A2-73.

This invention yet further includes a method of classifying cells as to sigma receptor type by the method of exposing said cells to a detectable amount of {circle around (−)} A2-73 substantially free of ⊕ A2-73 and determining the level of sigma receptor binding.

BACKGROUND OF THE INVENTION

Two sigma receptor subtypes have been identified based on their pharmacological profile. The sigma-1 (σ-1) receptor has been cloned (Hanner et al., 1996). The sigma-2 receptor has been reported as a separate molecular entity (Langa et al., 2003). The sigma-1 receptor has been reported as having high affinity for positive isomer of bezomorphas such as (+)-pentazocine and (+)-SKF-10,047. The sigma-2 receptor has been reported as having a high affinity for ibogaine (Vilner and Bowen, 2000). In particular, sigma 1 receptor agonists have also been has been reported as having antidepressant effects. In this regard, Sigma 1 receptor ligands show clear antidepressant effects in several animal models. By way of example, the selective sigma 1 receptor agonists (+)-pentazocine, (+)-SKF-10,047, igmesine, OPC14523, DTG or SA4503 reduce the immobility time in the forced swim test or are active in the tail suspension test (Ukai et al. 1998, Matsuno et al., 1996, Tottori et al. 1997, Kinsora et al. 1998). U.S. Pat. No. 5,034,419 describes N-cycloalkylalkylamines, which is also reportedly a sigma 1 receptor agonist.

The sigma-1 receptor, first reported cloned in 1996, is a single polypeptide transmembrane protein comprising 223 amino acids. It is mainly located on the endoplasmic reticulum membrane. The sigma-1 receptor is reported to be expressed in ocular tissues including the cornea, lens and retina. It has also been reported to play a role in cell survival (Wang et al., Exp Cell Research, Vol. 312(8):1439-1446, 2006); Hayashi et al., Cell, Vol. 131(3):596-610, November 2007; Jiang et al., IOVS, Vol. 47(12):5576-5582, 2006).

Sigma receptor ligands have been reported to be neuroprotective. The sigma receptor ligand opipramol was reported as protected against ischemia in gerbils. In addition, other sigma ligands, including BMY-14802, caramiphen and haloperidol, exhibited properties in in vivo models that are consistent with protective effects (Pontecorvo et al., Brain Research Bulletin, Vol. 26:461-465, 1991). Several sigma ligands were reported to inhibit ischemia-induced glutamate release from hippocampal slice preparations in vitro (Lobner et al., Neuroscience Letters, Vol. 117:169-174, 1990). It has also been reported that the Sigma-1 receptor agonist (+)-pentazocine can protect the retinal cells against stress (Dun et al., IOVS, Vol. 48(10):4785-4794, 2007; Smith et al., IOVS, Vol. 49(9):4154-4161, 2008).

Iñiguez et al., has reported that treatment of Jurkat T cells with sigma-2 (σ-2) agonists decreased the induction of the expression of Interleukin (IL)-2, Tumor necrosis factor (TNF)-α, and Cyclooxygenase (COX)-2 by activated T cells in a dose-dependent manner. (“Inhibitory effects of sigma-2 receptor agonists on T lymphocyte activation,” Front. Pharmacol, 13 Mar. 2013|doi: 10.3389/fphar.2013.00023.) Reported effects take place at the transcriptional level since σ-2 agonists BD-737 and CB-184 diminished the activity of the promoters of those genes. Those immunosuppressive effects could be attributable to interference with transcription factor activation. Induced transcription mediated by Nuclear factor (NF)-κB or Nuclear Factor of Activated T cells (NFAT) was inhibited by σ-2 agonists. The authors suggested that these effects were specific for σ-2 agonists as no significant effects on T cell activation by σ-1 ligands PRE-084 [2-(4-Morpholinethyl)1 Phenylcyclohexanecarboxylate] and BD-1063 were found. By way of non-limiting example, reported σ-2 agonists include CB-64D, CB-184, BD-737, and haloperidol.

A receptor antagonist is a type of receptor ligand or drug that blocks or dampens agonist-mediated responses rather than provoking a biological response itself upon binding to a receptor. In pharmacology, antagonists have affinity but no efficacy for their cognate receptors, and binding will disrupt the interaction and inhibit the function of an agonist or inverse agonist at receptors. Antagonists mediate their effects by binding to the active (orthosteric=right place) site or to allosteric (=other place) sites on receptors, or they may interact at unique binding sites not normally involved in the biological regulation of the receptor's activity. Antagonist activity may be reversible or irreversible depending on the longevity of the antagonist-receptor complex, which, in turn, depends on the nature of antagonist-receptor binding. The majority of drug antagonists achieve their potency by competing with endogenous ligands or substrates at structurally defined binding sites on receptor.

Competitive as to an agonist or antagonists (also known as surmountable) reversibly binds the agonist or antagonist to receptors at the same binding site (active site) as the endogenous ligand or agonist/antagonist, but without activating the receptor. Agonists and antagonists “compete” for the same binding site on the receptor. Once bound, an antagonist will block the opposite functioning molecule from binding. The level of activity of the receptor will be determined by the relative affinity of each molecule for the site and their relative concentrations. High concentrations of a competitive agonist or antagonist will increase the proportion of receptors that the that molecule occupies, higher concentrations of the molecule will be required to obtain the same degree of binding site occupancy. In functional assays using competitive antagonists, a parallel rightward shifts of agonist dose—response curves with no alteration of the maximal response is observed.

The term “non-competitive” (sometimes called non-surmountable antagonists) can be used to describe two distinct phenomena: one in which the agonist or antagonist binds to the active site of the receptor, and one in which the agonist/antagonist binds to an allosteric site of the receptor. While the mechanisms are different in both of these phenomena, they are both called “non-competitive” because the end-results of each are functionally very similar. Unlike competitive, which affects the amount of agonist or antagonist necessary to achieve a maximal response but do not affect the magnitude of that maximal response, non-competitive agonist or antagonists reduce the magnitude of the maximum response that can be attained by any amount of agonist or antagonist. http://en.wikipedia.org/wiki/Receptor_antagonist_cite_note-Vauquelin2002-19

Sigma1—Without being bound by any particular theory it is believed that Sigma1 receptors regulate neurotransmission via the NMDA receptor and the release of neurotransmitters such as dopamine and acetylcholine. It is thus proposed that the sigma1 receptors play a role in learning and memory as well as in certain neuropsychiatric disorders.

Antagonists—Sigma1 antagonists are believed useful in treating schizophrenic associated symptoms of blunted affect, anhedonia, avolition or apathy, and alogia. Sigma1 antagonists are also believed useful in attenuating orofacial dyskinesias and dystonic reactions associated as side-effects of physochotropic drugs. Sigma1 antagonists are also believed useful as cancer anti-proliferatives.

Agonists—Sigma1 agonists are useful as antidepressants. Particular note is made of the utility of a Sigma1 agonist with low Sigma2 affinity in treating ischemic brain/neuronal injury such as from focal ischemia. Sigma1 agonists are also believed useful in improving cognitive impairment such as exhibited with impaired neurotransmitter function (e.g., acetylcholine) as well as age associated cognitive impairment, and anxiety associated impairment (including pregnancy stress resulting in learning deficits of offspring).

Sigma2—Sigma2 receptors are believed useful as a target for motor function and cancer treatment. Sigma2 receptors are expressed in high densities in rapidly proliferating cancer cells.

Antagonists—Sigma2 antagonists are useful in the treatment of irreversible motor side effects such as those reported after the long-term administration of typical antipsychotic drugs.

Reference is made to Sigma Receptors: Chemistry, Cell Biology and Clinical Implications, Eds Matsumoto et al., Springer; 2007 edition (Nov. 16, 2014). The teaching of this publication and all references cited herein are incorporated by reference in their entirety. Additional reference is made to:

-   Nguyen et al., “Role of sigma-1 receptors in neurodegenerative     diseases,” J Pharmacol Sci. 2015 January; 127(1):17-29; -   Guo et al., Sigma-2 receptor ligands: neurobiological effects,” Curr     Med Chem. 2015; 22(8):989-1003; -   U.S. Ser. No. 62/065,833 entitled “A19-144, A2-73 and Certain     Anticholinesterase Inhibitor Compositions and Method for     Anti-Seizure Therapy,” filed Oct. 20, 2014; -   Crawford et al., “Sigma-2 Receptor Agonists Activate a Novel     Apoptotic Pathway and Potentiate Antineoplastic Drugs in Breast     Tumor Cell Lines,” Cancer Research, 62, 313-322, Jan. 1, 2002; -   Rossi et al., “A step forward in the sigma enigma: a role for     chirality in the sigma1 receptor-ligand interaction?” Medicinal     Chemistry Communication (Impact Factor: 2.63). September/2014; 6(1); -   U.S. Pub. No. 20110206780 entitled “Morphinan modulators of nmda     receptors, sigma1 receptors, sigma2 receptors, and/or a3b4 nicotinic     receptors,” to Gant et al., having a priority date of Jan. 6, 2010. -   WO2013008044 to Vamvakides et al. entitled “SYNTHESIS OF (+) AND (−)     1-(5,5-DIPHENYLTETRAHYDROFURAN-3-YL)-N,N-DIMETHYLMETHANAMINE, (+)     AND (−) 1-(2,2-DIPHENYLTETRAHYDROFURAN-3-YL)-N,N-DIMETHYLMETHANAMINE     AND (+) AND (−)     1-(2,2-DFFHENYLTETRAHYDROFURAN-3-YL)-N-METHYLMETHANAMINE” sets fort     chiral separatory methodology. -   U.S. Patent application entitled “ANAVEX2-73 FOR THE TREATMENT OF     ALZHEIMER'S DISEASE” and filed on date even herewith. -   U.S. Patent Application entitled “CRYSTAL FORMS OF     tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine     hydrochloride, PROCESSES OF MAKING SUCH FORMS, AND THEIR     PHARMACEUTICAL COMPOSITIONS” and filed on date even herewith.

SUMMARY OF THE INVENTION

A pharmaceutical preparation comprising {circle around (−)} A2-73 substantially free of ⊕ A2-73.

This invention further includes a method of therapeutic treatment of a subject in need of enhanced stimulation of sigma 1 receptors by administering a therapeutically effective dose of pharmaceutical preparation comprising {circle around (−)} A2-73 substantially free of ⊕ A2-73. Particularly noted is the pharmaceutical preparation of {circle around (−)} A2-73 substantially free of ⊕ A2-73 of from about 0.5 to about 100 mg {circle around (−)} A2-73 and particularly 1-20 mg.

A method of treating Alzheimer's disease in a subject in need of such treatment by the method of administering a therapeutically effective amount of {circle around (−)} A2-73 substantially free of ⊕ A2-73.

Further noted is a method of classifying cells as to sigma receptor type by the method of exposing said cells to a detectable amount of {circle around (−)} A2-73 substantially free of ⊕ A2-73 and determining the level of sigma receptor binding

DETAILED DESCRIPTION OF THE INVENTION

This invention will be better understood with reference to the following definitions:

A. ANAVEX2-73, or A2-73 shall mean tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine hydrochloride. This is listed in some of the test data as AE 37. A2-73 is a compound which is believed to bind to muscarinic acetylcholine and sigma-1 receptors with affinities in the low micromolar range.

B. ANAVEX19-144 or A19-144 shall mean 1-(2,2-diphenyltetrahydrofuran-3-yl)-N-methylmethanamine hydrochloride. A19-144 is a compound which is believed to bind to muscarinic acetylcholine and sigma-1 receptors with affinities in the low micromolar range.

C. ANAVEX1-41 or A1-41 shall mean tetrahydro-N,N-dimethyl-5,5-diphenyl-3-furanmethanamine hydrochloride. This is listed in some of the test data as AE 14. A1-41 is reported in Villard et al., “Antiamnesic and Neuroprotective Effects of the Aminotetrahydrofuran Derivative ANAVEX1-41 Against Amyloid b25-35-Induced Toxicity in Mice,” Neuropsychopharmacology, 1-15 (2008).

D. The term “enantiomer” or “enantiomeric” refers to a molecule that is nonsuperimposeable on its minor image and hence optically active wherein the enantiomer rotates the plane of polarized light in one direction and its minor image rotates the plane of polarized light in the opposite direction.

E. “Substantially free” as to defining enantiomers ⊕ form absent {circle around (−)} form or {circle around (−)} form absent ⊕ form shall mean less than about 2% (w/w) of the excluded form and preferably less than about 1% and more preferably less than about 0.5%, and in some cases less than about 0.1%.

F. “Classifying” cells as to the σ1 or 2 receptor populations shall mean determining the presence and or density of either σ1 or 2 receptors on cell surfaces in a given cell population. Classifying takes advantage of the differential populations of sigma receptors used as biomarkers. Biomarkers are useful as a means to define cell population propensities such as the likelihood of proliferation as to breast cancers. Testing methodology is more fully set forth in the following:

-   Hashimoto et al., “Sigma receptor ligands: possible application as     therapeutic drugs and as radiopharmaceuticals,” Curr Pharm Des.     2006; 12(30):3857-76; -   Mach R H et al., “Sigma 2 receptors as potential biomarkers of     proliferation in breast cancer,” Cancer Res 1997; 57: 156-61; -   Al-Nabulsi, I et al., “Effect of ploidy, recruitment, environmental     factors, and tamoxifen treatment on the expression of sigma-2     receptors in proliferating and quiescent tumour cells,” Br J Cancer     1999; 81: 925-33; and, -   Wheeler K T et al., “Sigma-2 receptors as a biomarker of     proliferation in solid tumours,” Br J Cancer 2000; 82: 1223-32.

A2-73 {circle around (−)} is a selective noncompetitive agonist for al receptors and a significantly stronger agonist than A2-73 ⊕.

The pharmacologically active compositions of this invention can be processed in accordance with conventional methods of Galenic pharmacy to produce medicinal agents for administration to subjects, e.g., mammals including humans.

Studies were conducted to on the effects of several compounds in various in vitro receptor binding and isolated organ assays.

1. Materials and Methods

1.1. In Vitro Pharmacology: Binding Assays

1.1.1. General Procedures Reference Assay Origin Compound Bibliography σ₁ (h) Jurkat cells haloperidol Ganapathy et al. (1999) σ₂ rat cerebral cortex haloperidol Bowen et al. (1993)

1.1.2. Experimental Conditions Non Method of Assay Ligand Conc. Specific Incubation Detection σ₁ (h) [³H](+)pentazocine 8 nM haloperidol 120 Scintillation (10 μM) min./22° C. counting σ₂ [³H]DTG 5 nM haloperidol 120 Scintillation (+300 nM (10 μM) min./22° C. counting (+)pentazocine)

As a general statement, in vitro results showing an inhibition (or stimulation for assays run in basal conditions) higher than 50% are considered to represent significant effects of the test compounds. 50% is the most common cut-off value for further investigation (determination of IC₅₀ or EC₅₀ values from concentration-response curves).

Results showing an inhibition (or stimulation) between 20% and 50% are indicative of weak to moderate effects (in some assays, they may be confirmed by further testing as they are within a range where more inter-experimental variability can occur).

Results showing an inhibition (or stimulation) lower than 20% are not considered significant and mostly attributable to variability of the signal around the control level.

Low to moderate negative values have no real meaning and are attributable to variability of the signal around the control level. High negative values (≥50%) that are sometimes obtained with high concentrations of test compounds are generally attributable to non-specific effects of the test compounds in the assays.

1.1.3. Analysis and Expression of Results

The specific ligand binding to the receptors is defined as the difference between the total binding and the nonspecific binding determined in the presence of an excess of unlabelled ligand.

The results are expressed as a percent of control specific binding and as a percent inhibition of control specific binding obtained in the presence of the test compounds. Individual and mean values are presented in the results section.

The IC₅₀ values (concentration causing a half-maximal inhibition of control specific binding) and Hill coefficients (n_(H)) were determined by non-linear regression analysis of the competition curves using Hill equation curve fitting. The inhibition constants (K_(i)) were calculated from the Cheng Prusoff equation (K_(i)=IC₅₀/(1+(L/K_(D))), where L=concentration of radioligand in the assay, and K_(D)=affinity of the radioligand for the receptor).

1.2. In Vitro Pharmacology: Isolated Organ Bioassay

1.2.1. General Procedures Reference Reference Biblio- Assay Tissue agonist Response antagonist graphy M₁ rabbit vas McN-A-343 inhibition of pirenzepine Eltze (1988) deferens twitch (field- contraction stimulated)

1.2.2. Experimental Conditions

Prostatic segments of rabbit vas deferens were suspended in 20-ml organ baths containing an oxygenated (95% O₂ and 5% CO₂) and pre-warmed (30° C.) physiological salt solution of the following composition (in mM): NaCl 118.0, KCl 4.7, MgSO₄ 0.6, CaCl₂ 2.5, KH₂PO₄ 1.2, NaHCO₃ 25 and glucose 11.0 (pH 7.4).

Yohimbine (1 μM) and naloxone (1 μM) were also present throughout the experiments to block the α₂-adrenergic and opioid receptors, respectively.

The tissues were connected to force transducers for isometric tension recordings. They were stretched to a resting tension of 1 g then allowed to equilibrate for 60 min during which time they were washed repeatedly and the tension readjusted. Thereafter, they were stimulated electrically with square wave pulses (submaximal intensity, 1 msec duration, 0.1 Hz) delivered by a constant current stimulator.

The experiments were carried out using a semi-automated isolated organ system possessing eight organ baths, with multichannel data acquisition.

1.2.3. Experimental Protocols

Test for Agonist Activity

The tissues were exposed to a submaximal concentration of the reference agonist McN-A-343 (1 μM) to verify responsiveness and to obtain a control response. Following washings and recovery of the initial twitch contractions, the tissues were exposed to the test compounds or the same agonist which were left in contact with the tissues until a stable response was obtained or for a maximum of 15 min.

If an agonist-like response (inhibition of twitch contractions) was obtained, the reference antagonist pirenzepine (0.1 μM) was tested against the test compounds to confirm the involvement of the M₁ receptors in this response.

Test for Antagonist Activity

The tissues were exposed to a submaximal concentration of the reference agonist McN-A-343 (1 μM) to obtain a control response.

After stabilization of the McN-A-343-induced response, the tissues were exposed to the test compounds or the reference antagonist pirenzepine which were left in contact with the tissues until a stable response was obtained or for a maximum of 15 min. If it occurred, a recovery of the twitch contraction amplitude by the test compounds indicated an antagonist activity at the M₁ receptors.

1.2.4. Analysis and Expression of Results

The parameter measured was the maximum change in the amplitude of the electrically-evoked contractions induced by the compounds.

The results are expressed as a percent of the control response to McN-A-343 (mean values).

Compounds

1.3. Test Compounds From: EURO GENET Lab A.E. CEREP Compound Reference Submitted Stock Intermediate I.D. I.D. Number F.W. Solution Dilution 9327-1 (+) A1-41 318.00 1.E−02M 1.E−04M DMSO H20 1.E−02M Direct DMSO addition * 9327-2 (−) A1-41 318.00 1.E−02M 1.E−04M DMSO H2O 1.E−02M Direct DMSO addition * 9327-3 (+) A2-73 318.00 1.E−02M 1.E−04M DMSO H2O 9327-4 (−) A2-73 318.00 1.E−02M 1.E−04M DMSO H2O 5.E−02M Direct DMSO* addition * 9327-6 AdPhAE/C6 compound 376.00 1.E−02M 1.E−04M 6 DMSO H2O 9327-7 Al142Me/C8 compound 332.00 1.E−02M 1.E−04M 8 DMSO H2O 9327-8 Ad2PhPZMe/ compound 437.00 1.E−02M 1.E−04M C3 3 DMSO H2O 9327-9 AdPh3/VC7 compound 374.00 1.E−02M 1.E−04M VC7 DMSO H2O F.W.: Formula Weight *: for the isolated organ bioassay RESULTS

1.4. In Vitro Pharmacology: Binding Assays

The mean values for the effects of the test compounds are summarized in table 1-1. The individual data obtained with the test compounds are reported in table 1-2.

The IC₅₀ and K_(i) values for each reference compound are indicated in table 1-3. Each is within accepted limits of the historic average±0.5 log units.

1.5. Reference Compounds

In each experiment, the respective reference compound was tested concurrently with the test compounds in order to assess the assay suitability. It was tested at several concentrations and the data were compared with historical values. The assay was rendered valid if the suitability criteria were met, in accordance with the corresponding Standard Operating Procedure.

TABLE 1-1 Summary Results Assay Client Test % Inhibition of Cerep Compound Concentration Control Specific Compound I.D. I.D. (M) Binding σ₁ (h) 9327-1 (+) A1-41 1.0E−06 66 9327-2 (−) A1-41 1.0E−06 65 9327-3 (+) A2-73 1.0E−06 19 9327-4 (−) A2-73 1.0E−06 50 9327-6 AdPhAE/C6 1.0E−06 97 9327-7 Al142Me/C8 1.0E−06 63 9327-8 Ad2PhPZMe/C3 1.0E−06 81 9327-8 Ad2PhPZMe/C3 1.0E−05 95 9327-9 AdPh3A/C7 1.0E−06 95 9327-9 AdPh3/VC7 1.0E−05 102 σ₂ 9327-1 (+) A1-14 1.0E−06 42 9327-2 (−) A1-14 1.0E−06 59 9327-3 (+) A2-73 1.0E−06 14 9327-4 (−) A2-73 1.0E−06 −13 9327-6 AdPhAE/C6 1.0E−06 78 9327-7 Al142Me/C8 1.0E−06 17 9327-8 Ad2PhPZMe/C3 1.0E−06 −9 9327-8 Ad2PhPZMe/C3 1.0E−05 57 9327-9 AdPh3/VC7 1.0E−06 84 9327-9 AdPh3/C7 1.0E−05 106

TABLE 1-2 Individual Data Assay Client Test % of Control Specific Cerep Com- Compound Concentration Binding pound I.D. I.D. (M) 1^(st) 2^(nd) Mean σ₁ (h) 9327-1 (+) A1-41 1.0E−06 35.0 32.9 34.0 9327-2 (−) A1-41 1.0E−06 35.7 33.3 34.5 9327-3 (+) A2-73 1.0E−06 81.5 81.1 81.3 9327-4 (−) A2-73 1.0E−06 50.7 50.0 50.4 9327-6 AdPhAE/C6 1.0E−06 4.3 1.9 3.1 9327-7 Al142Me/C8 1.0E−06 46.2 28.1 37.1 9327-8 Ad2PhPZMe/C3 1.0E−06 22.1 15.1 18.6 9327-8 Ad2PhPZMe/C3 1.0E−05 5.0 5.7 5.4 9327-9 AdPh3/VC7 1.0E−06 7.5 2.6 5.0 9327-9 AdPh3/VC7 1.0E−05 −4.4 0.8 −1.8 σ₂ 9327-1 (+) A1-41 1.0E−06 60.0 56.8 58.4 9327-2 (−) A1-41 1.0E−06 41.0 40.3 40.7 9327-3 (+) A2-73 1.0E−06 88.9 83.2 86.1 9327-4 (−) A2-73 1.0E−06 126.1 100.6 113.4 9327-6 AdPhAE/C6 1.0E−06 19.6 24.6 22.1 9327-7 AI142Me/C8 1.0E−06 84.0 81.0 82.5 9327-8 Ad2PhPZMe/C3 1.0E−06 103.7 113.9 108.8 9327-8 Ad2PhPZMe/C3 1.0E−05 45.2 40.5 42.9 9327-9 AdPh3/VC7 1.0E−06 1.6 30.2 15.9 9327-9 AdPh3A/C7 1.0E−05 −11.1 −0.2 −5.7

TABLE 1-3 Reference Compound Data Assay IC₅₀ K_(i) Reference Compound (M) (M) n_(H) σ₁ (h) haloperidol 1.3E−08 1.1E−08 0.8 σ₂ haloperidol 1.5E−07 1.3E−07 1.1 haloperidol 1.0E−07 8.6E−08 0.6

1.6. In Vitro Pharmacology: Isolated Organ Bioassay

The effects of (+) A1-41, (−) A1-41 and (−) A2-73 investigated for agonist and antagonist activities at the muscarinic M₁ receptors in the rabbit vas deferens are presented in table 2-1 where those of the reference compounds are also reported.

In the field-stimulated rabbit vas deferens, the M₁ receptor agonist McN-A-343 induced a concentration-dependent decrease in the twitch contraction amplitude which was reversed by the antagonist pirenzepine in a concentration-dependent manner. In the untreated tissues, (+) A1-41, (−) A1-41 and (−) A2-73 did not decrease the twitch contraction amplitude but caused a slight to moderate increase.

In the tissues previously depressed with McN-A-343, (+) A1-41, (−) A1-41 and (−) A2-73 produced a concentration-dependent and almost complete recovery of the twitch contraction amplitude.

These results indicate that (+) A1-41, (−) A1-41 and (−) A2-73 behave as antagonists at the M₁ receptors.

TABLE 2-1 Effects of (+) AE 14, (−) AE 14 and (−) AE 37 investigated for agonist and antagonist activities at the muscarinic M₁ receptors in the rabbit vas deferens Test for agonist activity Control response to Responses to increasing McN-A-343 concentrations +pirenzepine Compounds (1.0E−06M) of the compounds (1.0E−07M) 1.0E−06M 1.0E−05M 5.0E−05M (+) AE 14 100 −16 −31 not tested (−) AE 14 100 −5 −8 not tested (−) AE 37 100 −20 −33 not tested 1.0E−07M 3.0E−07M 1.0E−06M McN-A-343 100 29 67 99 −5 Test for antagonist activity Control Responses to McN-A-343 response to (1.0E−06M) in the presence McN-A-343 of increasing concentrations Compounds (1.0E−06M) of the compounds 1.0E−06M 1.0E−05M 5.0E−05M (+) AE 14 100 13 1 (−) AE 14 100 20 9 (−) AE 37 100 16 −1 1.0E−08M 3.0E−08M 1.0E−07M pirenzepine 100 72 43 4

The results are expressed as a percent of the control response to McN-A-343 (decrease in twitch contraction amplitude) (mean values; n=2)

Example 1 Neuroprotection Against Beta Amyloid

A 67 year old male diagnosed with early stage Alzheimer's dementia is treated with 10 mg of {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕, once per week for three years. His mental function is tested quarterly and does not decrease over the period. On autopsy, his brain is found to contain senile plaques but very low content in amyloid peptide oligomers.

Example 2 Neuroprotection Against Oxidative Stress

A 29 year old female balloonist, anticipating anoxic stress, is orally administered 10 mgs of oral {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕ daily for 5 days preceding a balloon ascent. The balloonist ascends to 6,000 meters without oxygen assist and suffers no anoxic damage.

Example 3 Neuroprotection Against Neurotoxicity

A 37 year old male hazardous materials engineer, anticipating neurotoxic stress, is orally administered 1 mg of {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕, daily for 5 days preceding exposure to tetanus toxin. The engineer is exposed 0.1 ng/kg of said neurotoxin and suffers no damage.

Example 4 Neuroprotection in Stroke Patient

A 57 year old male enters the emergency room and is diagnosed with an ischemic event involving the middle cerebral artery, with symptomatology onset being less than 1 hr. Immediately, the patient is administered an i.v. supplemented with 1 mg of {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕ while blood supply to the restricted area is restored. Daily testing of cognitive and motor systems show no deficits in physical or mental capacities. In addition, CT/MRI imaging shows no signs of lesioning in the affected region, immediately following recovery and that this was maintained and confirmed by follow-up imaging and behavior testing.

Example 5 Neuroprotection Against Amyloid

An 80 year old female patient is diagnosed with AD and treated with 10 mg of {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕ daily for 3 yrs. The patient's cognitive score stabilizes and then increases slowly and regularly over the following months.

Dosing Information/Dosage Forms:

For {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕ dosages of about 0.01-100 mg/daily, preferably 0.5-10 mg/daily, more preferably 0.5-2 mg/daily are noted. Dosing once every two days (3 times a week) is noted. AD is a chronic disease, so staring treatment promptly with diagnosis is preferred.

Particular attention is drawn to the method of this invention comprising {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕ administration. In some instances therapeutic treatment includes administration of at least one cooperating acetylcholinesterase inhibitor (donepezil, galantamine, rivastigmine, or memantine), wherein at least one of said therapeutically effective amounts of either or the dose of cooperating acetylcholinesterase inhibitor is sub-therapeutic (sub-MAD) as compared to the active dose when used alone. Either the {circle around (−)} Anevex2-73 substantially free of Anavex2-73 ⊕ or the cooperating acetylcholinesterase inhibitor is used. In this regard, reference is made to U.S. Ser. No. 13/940,352 to Vamvakides et al entitled “ANAVEX2-73 AND CERTAIN ANTICHOLINESTERASE INHIBITORS COMPOSITION AND METHOD FOR NEUROPROTECTION” the teachings of which are incorporated herein by reference.

The compositions of this invention individually or in combination are employed in admixture with conventional excipients, i.e., pharmaceutically acceptable organic or inorganic carrier substances suitable for parenteral, enteral (e.g., oral or inhalation) or topical application which do not deleteriously react with the active compositions. Suitable pharmaceutically acceptable carriers include but are not limited to water, salt solutions, alcohols, gum arabic, vegetable oils, benzyl alcohols, polyethylene glycols, gelatin, carbohydrates such as lactose, amylose or starch, magnesium stearate, talc, titanium dioxide, silicic acid, viscous paraffin, perfume oil, fatty acid esters, hydroxy methylcellulose, polyvinyl pyrrolidone, etc. The pharmaceutical preparations can be sterilized and if desired mixed with auxiliary agents, e.g., lubricants, preservatives, stabilizers, wetting agents, emulsifiers, salts for influencing osmotic pressure, buffers, coloring, flavoring and/or aromatic substances and the like which do not deleteriously react with the active compositions. They can also be combined where desired with other active agents, e.g., vitamins.

In some embodiments of the present invention, dosage forms include instructions for the use of such compositions.

For parenteral application, particularly suitable are injectable, sterile solutions, preferably oily or aqueous solutions, as well as suspensions, emulsions, or implants, including suppositories. Ampules, vials, and injector cartridges are convenient unit dosages.

“Unit dosage form” shall mean single drug administration entity. By way of example, a single tablet, capsule, dragee, or trochee, suppository, or syringe.

Also for parenteral application, particularly suitable are tablets, dragees, liquids, drops, suppositories, or capsules. A syrup, elixir, or the like can be used wherein a sweetened vehicle is employed. Sublingual and buccal forms are also noted.

Sustained or directed release compositions can be formulated, e.g., liposomes or those wherein the active component is protected with differentially degradable coatings, e.g., by microencapsulation, multiple coatings, etc. It is also possible to freeze-dry the new compositions and use the lyophilizates obtained, for example, for the preparation of products for injection. 

The invention claimed is:
 1. A pharmaceutical dosage form of (−) Anavex2-73 substantially free of (+) Anavex2-73, wherein the pharmaceutical dosage form comprises less than about 2% (w/w) of (+) Anavex2-73.
 2. The pharmaceutical dosage form of claim 1 comprising from about 0.5 mg to about 100 mg of (−) Anavex2-73.
 3. The pharmaceutical dosage form of claim 2 comprising from about 1 mg to about 20 mg of (−) Anavex2-73.
 4. A method of therapeutic treatment of a subject in need of enhanced stimulation of sigma 1 receptors comprising administering a pharmaceutical dosage form according to claim 1 comprising a therapeutically effective amount of (−) Anavex2-73 substantially free of (+) Anavex2-73, wherein the subject suffers from at least one of ischemic brain injury, ischemic neuron injury, focal ischemia, neurotoxicity, stroke, and cognitive impairment.
 5. The method of claim 4 wherein said therapeutically effective amount comprises about 0.5 mg to about 100 mg of (−) Anavex2-73.
 6. The method of claim 5 wherein said therapeutically effective amount comprises from about 1 mg to about 20 mg of (−) Anavex2-73.
 7. A method of treating Alzheimer's disease in a subject in need of such treatment, the method comprising administering a pharmaceutical dosage form according to claim 1 comprising a therapeutically effective amount of (−) Anavex2-73 substantially free of (+) Anavex2-73.
 8. The method of claim 7 wherein said therapeutically effective amount comprises about 0.5 mg to about 100 mg of (−) Anavex2-73.
 9. The method of claim 8 wherein said therapeutically effective amount comprises from about 1 mg to about 20 mg of (−) Anavex2-73.
 10. The pharmaceutical dosage form of claim 1, wherein the pharmaceutical dosage form comprises less than about 1% (w/w) of (+) Anavex2-73.
 11. The pharmaceutical dosage form of claim 1, the pharmaceutical dosage form comprises less than about 0.5% (w/w) of (+) Anavex2-73.
 12. The pharmaceutical dosage form of claim 1, wherein the pharmaceutical dosage form comprises less than about 0.1% (w/w) of (+) Anavex2-73.
 13. The pharmaceutical dosage form of claim 1, wherein the dosage form comprises an admixture of excipients which do not react with (−) Anavex 2-73 or (+) Anavex2-73.
 14. The pharmaceutical dosage form of claim 1, wherein the pharmaceutical dosage form is a sustained release formulation or a direct release formulation.
 15. The pharmaceutical dosage form of claim 14, wherein the pharmaceutical dosage form comprises a parenteral formulation, an enteral formulation, or a topical formulation.
 16. The pharmaceutical dosage form of claim 14, wherein the pharmaceutical dosage form is a liposome formulation, or a lyophilized formulation.
 17. The pharmaceutical dosage form of claim 14, wherein the dosage form is in the form of a tablet, an oil suspension, an aqueous solution, a sterile solution, an injectable solution, a capsule, a dragree, a trochee, a suppository, a syrup, an elixir, a suspension, an emulsion, or an implant.
 18. The pharmaceutical dosage form of claim 14, wherein the dosage form comprises a sweetener.
 19. The method of claim 4, wherein the subject is a human subject. 